Just finished Shrinking, a TV show about therapy, how common is it for people to get therapy in the USA?

It’s quite common, but it’s also very expensive so many people who would benefit from it cannot afford it. Our insurance system is problematic enough that few therapists accept payment via insurance rather than directly.

It's common for the people who can afford it. Health insurance will fight you on covering it and most therapists try to operate with as little overhead as possible because it is not as reliable as primary care, for example. In other words, therapists generally don't like dealing with health insurers on the patient's behalf. It costs too much for them. This means that most end up paying out of pocket and it does not go against their deductible. I would put a rough estimate that really only the top 40% of earners in America have realistic, reliable access to it. And it will be a significant financial burden for those below top 20% of earners. Which means they will be unlikely to stick with it long-term.
- I've never heard of anyone paying out of pocket for therapy instead of going through insurance. I've had several different insurance providers over the past 15+ years and never had an issue getting therapy covered.
  
  I have had to pay for therapy out of pocket, and it's increasingly common for therapists to not accept insurance. There is a higher demand for therapy than a supply of therapists to meet that demand (esp. since the pandemic, but even before then), so many therapists realized they can just operate a practice without the hassle of dealing with insurance.
  
  Well, for instance, BetterHelp is not covered by any insurance, and that's probably the most accessible therapy for everyone. It has more to do with your therapist than the insurance. You probably have dealt with providers that work with insurance. I'm telling you there are a lot that don't for the reasons I outlined.
  I also think you're lucky or either the insurers are getting more bold about denying coverage. I've had to fight insurer's on two separate occasions regarding therapy.

not as common as it should be
a note about that show specifically: Pasadena is a well-to-do area and that's part of why so many people can afford those services
but as least one person is there by court order

Most of the people I know are in therapy, and those who aren't should do it. Therapy is the one time a week that you can just let your emotions out and not feel ashamed, and have someone help you see things from a different angle. Folks who don't get that chance either rely on their friends to trauma dump or bottle it all up.
- Is it common to do it weekly? I always did it monthly because the copays add up.
  
  weekly is common starting off, sometimes every two weeks - some therapists move to less frequent meetings once things have stabilized or just for check-ins on progress

Not nearly enough. When we lived on the east coast me and my kids were going to grief counseling and therapy after my oldest took their own life. When we moved back to my home state of NM there was nothing available that accepted our insurance. We could pay out of pocket and get a reimbursement… sometimes. We tried getting the kids into something through school (which is what they had back east, but there was nothing).

A fair number of friends and family have gotten counseling/therapy at one point or another for various things, be that depression, coming out, anxiety or interpersonal conflict. It universally helped everyone.
Everyone should have it. It's useful to have people give you solid advice, particularly ones that have no family or friend connections to you. It allows you to have very clear-eyed discussions.
It helped me immensely when I was struggling with coming out.

its common if your rich or poor enough to afford it in money and time but like many things in the us its tough if your in the middle and pretty low middle to. Like in a halfway house.

I would say it's pretty common as needed, though for many there's still a stigma about "being weak" or whatever. That's declined in my adult life (15 years or so). I'm sure there are statistics to compare with other countries though

One in five people between 18 and 44 have seen a therapist in the US, according to Statista.